The present invention relates generally to the vacuum cleaner art and, more particularly, to an upright vacuum cleaner incorporating a spring loaded nozzle.
Upright vacuum cleaners in all of their designs and permutations have become increasingly popular over the years. The upright vacuum cleaners generally incorporate a nozzle assembly and a canister assembly pivotally mounted to the nozzle assembly. Wheels on the nozzle and canister assemblies allow the vacuum cleaner to smoothly ride over the surface to be cleaned.
The canister assembly includes an operating handle that is manipulated by the user to move the vacuum cleaner back-and-forth across the floor. The canister assembly also includes either a bag-like filter or a cyclonic separation chamber and filter combination that trap dirt and debris while substantially clean air is exhausted by a fan that is driven by an onboard electric motor. It is this fan and motor arrangement that generates the drop in air pressure necessary to provide the desired cleaning action.
In most upright vacuum cleaners sold today, a rotary agitator is also provided in the nozzle assembly. The rotary agitator includes tufts of bristles, brushes, beater bars or the like to beat dirt and debris from the nap of a carpet being cleaned while the pressure drop or vacuum is used to force air entrained with this dirt and debris into the nozzle of the vacuum cleaner.
As the vacuum cleaner is manipulated back-and-forth by the operator with the handle on the canister assembly, the nozzle assembly is periodically lifted slightly from the floor. This lifting action adversely affects the cleaning efficiency of the vacuum cleaner. Further, during the cleaning of certain surfaces there is a tendency for vibration to develop in the vacuum cleaner as a result of the engagement of the rotary agitator against the particular surface being cleaned. This vibration is often transmitted through the control handle and is often annoying to the user. A need is therefore identified for an upright vacuum cleaner that addresses these problems in a manner to provide enhanced cleaning efficiency as well as vibration reduction.
In accordance with the purposes of the present invention as described herein, an improved upright vacuum cleaner is provided. That vacuum cleaner includes a nozzle assembly and a canister assembly pivotally mounted to the nozzle assembly. A suction fan and motor are carried on one of the nozzle assembly and the canister assembly. Additionally, the upright vacuum cleaner includes a means, such as a biaser, having a first end engaging the nozzle assembly and a second end engaging the canister assembly. This biaser provides a positive downforce urging a forward end of the nozzle assembly toward the surface to be cleaned. This urging not only enhances cleaning efficiency but also serves to dampen vibration.
In accordance with additional aspects of the present invention, the biaser may be a torsion spring. Further, the nozzle assembly may include a hollow stub shaft received within a cooperating groove in the canister assembly. That stub shaft defines an axis for pivoting movement of the canister assembly with respect to the nozzle assembly as the vacuum cleaner is manipulated by the user. At least a portion of the spring is received in this hollow stub shaft.
Still further, the canister assembly may include a channel adjacent the groove and the second end of the spring is elongated and received in that channel. The channel may be formed, for example, by a box rib on the wall of the canister assembly. Additionally, the hollow stub shaft may include a slot in the side wall thereof through which the end of the spring extends into the channel.
The spring is selected to provide between about 1.2 and about 3.2 lbs/sq. in. of preload and more typically between about 2.0 and about 2.4 lbs/sq. in. of preload. Such a spring provides between about 0.2 and 3.0 lbs/sq. in. of downforce on a forward end of the nozzle assembly. In a typical arrangement, the spring is selected to provide a downforce of between about 0.8 and about 1.6 lbs/sq. in. (e.g. about 1.2 lbs/sq. in.) of downforce on a forward end of the nozzle assembly when the canister assembly is positioned at about a 135xc2x0 included working angle with respect to the nozzle assembly: that is, when the canister assembly forms an included angle of about 45xc2x0 with the floor being cleaned.
The resulting downforce reduces the vibration of the nozzle assembly and advantageously increases the cleaning efficiency of the vacuum cleaner by maintaining the nozzle assembly in close engagement with the surface being cleaned. This is a particular advantage as vibration may even be controlled in canister and nozzle assemblies constructed from lighter weight materials. Such materials allow the production of more lightweight vacuum cleaners that are particularly favored by consumers since they are easier to handle and require less muscle effort to use.
The invention also includes a method of increasing the cleaning efficiency of a vacuum cleaner by providing a downforce on the nozzle assembly of the vacuum cleaner to urge the nozzle assembly toward the floor being cleaned.
Still further, the invention also includes a method of reducing vibration in a vacuum cleaner by providing a biasing force between the nozzle assembly and the canister assembly to dampen vibration produced by engagement of the rotary agitator with the surface being cleaned.
In the following description there is shown and described one possible embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.